Optical fiber ribbons, in which a plurality of single-core optical fibers arranged parallel to one another are collectively coated with a common resin, are known. Such an optical fiber ribbon allows a large amount of information to be transmitted therethrough and is easily handled.
Multi-core optical fibers are also known. In the multi-core optical fibers, a plurality of cores that each extends in the axial direction of the fiber and serves as a high refractive-index component are coated with a common cladding. A multi-core optical fiber ribbon can be produced by collectively coating the plurality of multi-core optical fibers arranged parallel to one another with a common resin. Such a multi-core optical fiber ribbon is expected to allow a larger amount of information to be transmitted therethrough.